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International Journal of Engineering and Technical Research (IJETR)
ISSN: 2321-0869 (O) 2454-4698 (P), Volume-7, Issue-5, May 2017

The Amalgamation Performance Analysis of the LCI
and VSI Fed Induction Motor Drive
Shashank Kumar Singh, Mr. Imran Khan

Abstract— In this paper combination of a load-commutated
inverter (LCI) and a voltage-source inverter (VSI) are employed
for performance analysis of induction motor drive. Induction
motors are the starting point to design an electrical drive system
which is widely used in many industrial applications. In modern
control theory, different mathematical models describe
induction motor according to the employed control methods.
Vector control strategy can be applied to this electrical motor
type in symmetrical three phase version or in unsymmetrical
two phase version. The operation of the induction motor can be
analyzed similar to a DC motor through this control method. In
this control scheme the electromagnetic torque and stator flux
magnitude are estimated with only stator voltages and currents
and this estimation does not depend on motor parameters except
for the stator resistance. There is an increasing trend of using
SVPWM, because of their easier digital realization and better
DC bus utilization. The study of SVPWM technique reveals that
this technique utilizes DC bus voltage more efficiently and
generates less harmonic distortion when compared with
sinusoidal PWM techniques. The SVPWM technique has
become one of the important PWM techniques for Three Phase
Voltage Source Inverter for the control of AC induction motor,
Brushless DC motor, Switched Reluctance motor and
Permanent Magnet Synchronous motor. In this paper having
collection of different schemes in SVPWM. Specifically various
schemes are Center aligned two level SVPWM, Level shifted
multi-carrier concepts based SVPWM.
This paper having simulation results of all the three schemes of
SVPWM by using MATLAB/SIMULINK software. The
performance of Three Phase Voltage Source Inverter fed
induction motor drive based on various SVPWM schemes are
analyzed by various reference parameters like DC bus
utilization. The simulation results are provided to validate the
proposed model approaches.

drives have been used in high-power applications, because of
an economical and reliable current source inverter using
IGBT-diode and the rugged induction motors [5]. The
LCI-based drive employs converter grade utilizes soft
switching by natural commutation of the IGBT-diode.
Voltage Source Inverter (VSI) fed Induction Motor drive is an
attractive solution for low power applications because of the
availability of fast switching devices like IGBT and
MOSFET. But for medium and high power applications, VSI
can not switch as fast as in the case of low power counterpart
due to increased switching loss. Furthermore, for medium
voltage applications, the devices of required voltage rating for
two levels VSI are not readily available. Multilevel VSI [1]
are used in medium voltage applications as the device voltage
stress decreases with the increase in the number of levels of
multilevel VSI.

Index Terms-- Diode rectifier, Induction motor, Load
commutated inverter (LCI), SVPWM technique, Voltage source
inverter (VSI).
I.

INTRODUCTION

Over the past decades DC machines were used extensively for
variable speed applications due to the decoupled control of
torque and flux that can be achieved by armature and field
current control respectively. DC drives are advantageous in
many aspects as in delivering high starting torque, ease of
control and nonlinear performance. But due to the major
drawbacks of DC machine such as presence of mechanical
commutator and brush assembly, DC machine drives have
become obsolete today in industrial applications. The voltage
source inverter fed Induction motor drives most commonly
controlled through the pulse width-modulation technique.
Load-commutated inverter (LCI)-based induction motor

Figure 1 Control block diagram of LCI and VSI fed induction
motor
II. PROPOSED SYSTEM ARCHITECTURE
The proposed drive system consisting of a diode rectifier, an
LCI, a VSI, an LC filter and three phase induction motor are
shown in Fig. 1. The VSI is connected with the LCI in parallel
through capacitor DC link.LCI and VSI energized through the
same DC link output but the different element. A large
inductor DC link is employed for the load commutated
inverter. LCI, in order to convert uncontrolled DC voltage to
controlled DC current. The DC-link current regulated by the
inductor is supplied to the LCI. As a result, both the VSI and
the LCI can be fed from the single-diode rectifier. The VSI
generates sinusoidal phase voltage to the induction motor.

Shashank Kumar Singh, Department of Electrical Engineering, M.Tech
Scholar, Azad Institute of Engineering & Technology, Lucknow, India.
Mr. Imran Khan, Associate Professor, Department of Electrical
Engineering, Azad Institute of Engineering & Technology, Lucknow, India.

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Modeling and Performance Analysis of Hybrid Power System for Residential Application
The amplitude and frequency of the VSI output voltage is
continuously regulated by the motor speed control. In
addition, the phase angle of the VSI output voltage is set from
adjusting the firing angle of the LCI to provide a safe LCI
commutation angle. Therefore, the leading power factor for
the LCI operation is entirely obtained by the VSI over the
whole speed range of the induction motor. Based on the
leading power factor by the VSI, the presented system can
operate the LCI without the dc-commutation circuit as well as
output capacitors. Therefore, the employed system can
successfully solve all problems caused by the output
capacitors and the forced dc-commutation circuit of the
conventional LCI-based induction motor. Another advantage
by bringing the VSI is to generate sinusoidal motor currents
for all speed regions to large induction motor drives. The
parallel assembly of the LCI and the relatively small-size VSI
is expected to fulfill the high-power applications, where a
stand-alone VSI cannot be utilized to generate sinusoidal
motor currents. In addition, the sinusoidal motor voltages are
also achieved through the LC filter.

Figure 2 Inverter switching state vectors
The control processing unit calculates the basic parameters to
apply a switching state. The input data to the control
processing unit is the reference space vector. During various
iterations, the unit determines the sector number, triangle
number of the subhexagon. The sector number and triangle
number identify the correct switching sequence. The
flowchart is given for an n-level inverter and can be used for
any n-levels without change. The flow diagram of the
proposed algorithm to find minimum THD is shown in Figure
3

III. SVPWM CONTROL TECHNIQUE
PWM drive is advantageous in many ways, for example it
obtains its dc input through uncontrolled rectification of
commercial AC mains and has good power factor, good
efficiency, relatively free from regulation problems, it has the
ability to operate the motor with nearly sinusoidal current
waveform. The conventional PWM techniques are suitable
for open loop control, for the implementation of a closed loop
controlled AC drive Space vector PWM (SVPWM) technique
is applied. In this technique, the switching patterns for the
bridge inverter are generated from the knowledge of stator
voltage space phasor. A reference voltage vector is generated
to generate a field synchronous with the rotating voltage
vector by utilizing the different switching states of a three
phase bridge inverter [15]. The SVPWM is considered as a
better technique of PWM implementation as it has advantages
over SPWM in terms of good utilization of dc bus voltage,
reduced switching frequency and low current ripple. When
three phase supply is given to the stator of the induction
machine, a three phase rotating magnetic field is produced.
Due to this field flux, a three phase rotating voltage vector is
generated which lags the flux by 90º. This field can also be
realized by a logical combination of the inverter switching
which is the basic concept of SVPWM. The three phase
bridge inverter has eight possible switching states: six active
and two zero states. The six switches have a well-defined state
ON or OFF in each configurations. At a particular instant,
only one switch in each of the three legs is ON.
Corresponding to each state of
the inverter, there is one voltage space vector. For example
for state zero it is V0, for state 1 it is V1 and so on. These
switching state vectors have equal magnitude but 60º apart
from each other [8]. These vectors can be written in
generalized form as follows:

Figure 3 Flowchart of SVPWM Algorithm
IV. SYSTEM MODEL
In this section simulation circuit model is developed to
examine the amalgamation performance of the LCI and VSI
fed induction motor drive. A three-phase squirrel-cage
induction motor rated 3 hp, 220 V, 60 Hz, 1725 rpm is fed by
a load commutated inverter and voltage source inverter. The
firing pulses to the inverter are generated by the SVPWM
modulator block of the SPS library. The chopping frequency
is set to 6000 Hz and the input reference vector to
magnitude-angle. Speed control of the motor is performed by
the constant V/Hz block.

Where k = inverter state number.
Vdc = dc link voltage of the inverter
The inverter state vectors can be drawn as shown in fig.2

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International Journal of Engineering and Technical Research (IJETR)
ISSN: 2321-0869 (O) 2454-4698 (P), Volume-7, Issue-5, May 2017
MODEL FOR HYBRID PERFORMANCE
INDUCTION MOTOR DRIVE

OF

Figure 7 Speed Acceleration (1000 rpm -1400rpm)
Figure 4 Main Model

Figure 5 starting (0-500rpm) Model
Figure 8 Speed Acceleration (1400 rpm -1725rpm)

Figure 9 Speed Deceleration (1725 rpm -1400rpm)

Figure 6 Speed Acceleration (500 rpm - 1000rpm)

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Modeling and Performance Analysis of Hybrid Power System for Residential Application

Figure 13 Acceleration in load torque (0N-m -18N-m)

Figure 10 Speed Deceleration (1400 rpm -1000rpm)

Figure 11 Speed Deceleration (1000 rpm -500rpm)

Figure 14 Deceleration in load torque (18N-m - 8N-m)

Figure12 Deceleration in Load Torque (11.9N-m - 0N-m)

Figure 15 Acceleration in load torque (8N-m - 11.9N-m)

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International Journal of Engineering and Technical Research (IJETR)
ISSN: 2321-0869 (O) 2454-4698 (P), Volume-7, Issue-5, May 2017
V. RESULTS
DRIVE PERFORMANCE
Case–1: Starting (0 to 500 rpm)

Case–3: Speed acceleration (1000rpm to 1400 rpm)

Figure 18 Speed Acceleration 0 to 500 rpm

Figure 16 Speed Acceleration 0 to 500 rpm

Case–4: Speed acceleration (1400rpm to 1725 rpm)

Case–2: Speed acceleration (500rpm to 1000 rpm)

Figure 19 Speed Acceleration (1400rpm to 1725 rpm)

Figure 17 Speed Acceleration 0 to 500 rpm

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Modeling and Performance Analysis of Hybrid Power System for Residential Application
Case–5: Speed Deceleration (1725 rpm to 1400rpm)

Case–7: Speed deceleration (1000 rpm to 500 rpm)

Figure 22 Speed Deceleration (1000 rpm to 500 rpm)
Figure 20 Speed Deceleration (1725 rpm to 1400rpm)
Case–8: Decrease in load torque (11.9 N-m to 0 N-m)

Case–6: Speed Deceleration (1400 rpm to 1000 rpm)

Figure 21 Speed Deceleration (1400 rpm to 1000 rpm)

Figure 23 Decrease in load torque (11.9 N-m to 0 N-m)

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International Journal of Engineering and Technical Research (IJETR)
ISSN: 2321-0869 (O) 2454-4698 (P), Volume-7, Issue-5, May 2017
Case–9: Increase in load torque (0 N-m to 18 N-m)

Case–11: Increase in Load Torque (8 N-m to 11.9 N-m)

Figure 26 Increase in load torque (8 N-m to 11.9 N-m)
Figure 24 Increase in load torque (0 N-m to 18 N-m)
DC WAVEFORM

Case–10: Decrease in Load Torque (18 N-m to 8 N-m)

Figure 27 DC Waveform
Figure 25 Decrease in load torque (18 N-m to 8 N-m)

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Modeling and Performance Analysis of Hybrid Power System for Residential Application
[3] Peters GL, Covic GA, Boys JT. “Eliminating output distortion in
four-switch inverters with three phase loads,” IEE Proc Electron Power
Appl 1998; 145(4): 326-32.
[4] G.Kim and T A. Lipo, “VSI-PWM rectifier/inverter system with a
reduced switch count,” in Proc. IEEE-IAS Annual Meeting, 1995,
pp.2327-2332.
[5] Nasir Uddin, M., T.S. Radwan and M.A. Rahman, 2004. “Performance
analysis of four switch 3- phase inverter-fed IM drives,” Proceeding of
the CD-ROM of the 3 rd IEEE International Conference.
[6] Miaosen Shen, Alan Joseph, Jin Wang, Fang Z. Pengl, Donald J. Adams
“Comparison of traditional inverters and Z-source inverter for fuel cell
vehicles,” IEEE 0-7803-8538- 1,2004.
[7] Hossein Madadi Kojabadi.” A comparative analysis of different pulse
width modulation methods for low cost induction motor drives” Energy
Conversion and Management, .
[8] Ciro Attainese, Aldo Perfetto and Giuseppe Tomasso, June 2002, “ A
space vector modulation Algorithm for Torque control of Inverter fed
Induction Motor Drive”, proceedings of the IEEE Transactions On
Energy Conversion, vol.17, no.2, 222-228.
[9] T. Brahmananda Reddy, B.Kalyan Reddy, J. Amaranth, D. Subba
Rayudu and Md. Haseeb Khan, June 2006, “Sensorless Direct Torque
Control of Induction Motor based on Hybrid Space Vector Pulse width
Modulation to Reduce Ripples and Switching Losses – A Variable
Structure Controller Approach”, proceedings of IEEE Transactions,
0-7803-9525-5/06.
[10] S.Chakrabarti, M. Ramamoorthy and V.R.Kanetkar, 1997, “Reduction
of Torque Ripple in Direct Torque Control of Induction Motor Drives
Using Space Vector Modulation Based Pulse Width Modulation”
Proceedings of IEEE Transactions,7803-3773-5/97
[11] Ebenezer V., K.Gopakumar and V.T.Ranganathan, 1998, “A Sensorless
Vector Control Scheme for Induction Motors using a Space Phasor
based Current Hysteresis Controller”, proceedings of IEEE
Transactions, 26-31.
[12] D. Hadiouche, H. Razik and A. Rezzoug, September 2000, “Study and
Simulation of Space Vector PWM Control of Double-Star Induction
Motors”,Proceedings of IEEE Transactions 42-47.
[13] Joao O.P. Pinto, Bimal K.Bose, and Luiz Eduardo Borges da Silva,
September/October 2001, “ A Stator-flux-oriented Vector-Controlled
Induction Motor Drive With Space- Vector PWM and Flux-Vector
Synthesis by Neural Networks”, proceedings of IEEE Transactions on
Industry Applications, Vol.37, No.5, 1308-1318.
[14] Pedro Ponce, Juan C. Ramirez, April 2004, “Fuzzy Logic Controller
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[15] S Allirani, V Jagannathan, “High Performance Direct Torque Control of
Induction Motor Drives Using Space Vector Modulation” IJCSI, Vol. 7,
Issue 6, November 2010.

LCI CONTROL VOLTAGE

Figure 28 LCI Voltage
VI. CONCLUSION
In this paper, describes LCI and VSI fed three-phase
induction motor drive is simulated, fabricated and tested. The
reliability is increased by using microcontroller as the on chip
intelligent controller. The experimental results closely agree
with the simulation results. Modified Sine PWM is used to
reduce switching losses. The contribution of this work is the
development of modified Sine PWM model using the blocks
of simulink. Modified Sine PWM inverter fed induction
motor drive is a viable alternative to the VSI fed induction
motor drive due to the reduced switching losses. The present
work indicates that SVM inverter fed induction motor drive is
an economical drive with reduced harmonics Sine PWM and
SVM inverter fed induction motor drives are compared. The
performance of the Load Commutated Inverter fed induction
motor drive has been investigated through the
MATLAB/Simulation for the different alteration in reference
speed and load torque. Simulation results shows that the
presented drive system provides the more satisfactory results
than the conventional CSI and VSI.

Shashank Kumar Singh, Department of Electrical Engineering, M.Tech
Scholar, Azad Institute of Engineering & Technology, Lucknow, India.
Mr. Imran Khan, Associate Professor, Department of Electrical
Engineering, Azad Institute of Engineering & Technology, Lucknow, India

REFERENCES
[1] Van der Broeck HW, Van Wyk JD. “A comparative investigation of a
three phase induction machine drive with a component minimized
voltage fed inverter under different control options,”IEEE Trans Ind
Appl 1984; 20(2): 309-20.
[2] Van der Broeck HW, Skudelny HC. “Analytical analysis of the harmonic
effects of a PWM ac drive,” IEEE Trans Power Electron 1988;3:
216-23.

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